Not applicable.
1. Field of the Invention
This invention relates to aircraft communications systems for voice and/or data, and in particular to such systems using optical frequencies for communication aboard the aircraft and radio frequencies for external communications.
2. Description of the Related Art
Every experienced traveler is aware of the prohibition aboard airliners of devices such as personal telephone handsets which emit energy at radio frequencies. During critical periods of the flight such as take-off and landing, the ban is expanded to include all electronic equipment, including lap-top computers. The reason for the ban is that stray radio-frequency (RF) emissions from such equipment might interfere with electronic systems which control or aid in the navigation of the aircraft.
Personal telephone handsets, which include cellular and PCS telephones, personal digital assistants (PDAs), and similar devices which emit RF signals for communications, cannot be used at anytime during flight because they emit RF radiation that may interfere with flight systems or with ground-based mobile telephone services. The frequencies involved may vary in countries other than the United States, but the problem remains the same; the aircraft navigation system and other systems can be affected by these frequencies or by intermodulation products of these frequencies with others.
Many travelers are professionals who need to make efficient use of their time, including travel time spent aboard aircraft. The ability to use their personal communications devices for voice, data, FAX, etc. aboard airliners would be a welcome advance. A need exists, therefore, for a system which will allow the use of personal electronic communications equipment aboard aircraft, without danger of interference with the aircraft""s on-board systems.
This invention is a communications system that permits the use of personal telephone handsets and other communications devices aboard passenger-carrying airliners and other aircraft. The invention uses an infrared (or other optical-frequency) communications network within the aircraft; voice and/or data signal traffic in the on-board system is managed by a controller/router. The controller/router is also an interface between the on-board system and transceivers connected to antennas. Communications with stations outside the aircraft includes sending RF signals to and from transmit/receive antennas. Remote stations with which the system antennas can communicate include satellites, other aircraft, and ground stations.
Recently manufactured computers and other electronic devices include infrared ports for transmitting and receiving signals at optical frequencies. This infrared capability is typically used for computer networking and data transfer. Many cellular and PCS (Personal Communications System) telephone handsets have infrared ports to replace the usual serial interface cable connection to computers for data transfer; this feature is increasingly common in newer equipment, and in some cases it allows the portable telephone to act as a sort of xe2x80x9cwireless modemxe2x80x9d for the computing device.
In this invention, infrared ports on the aircraft are linked to external radio-frequency (RF) antenna(s) for voice calls, facsimile transmissions, electronic mail, internet connections, data transfer, and other communications with stations outside the aircraft. In addition, intra-aircraft communications (between stations on board the aircraft) use the same system for circuit-switched (dial-up) or connectionless (packet) transfer of data aboard the aircraft. The same optical ports are used for intra-aircraft communications and for calls to or from stations outside the aircraft.
As outlined above, the system allows the shared use of communication resources by an aircraft crew and its passengers. Aircraft routing, navigation, weather, and telemetry services may use the same channels that the passengers use for voice, FAX, and data transmissions. These categories of transmissions include multi-media transmissions such as pictures, voice clips, etc. Allocation of channels is handled by the controller/router which gives priority to communications related to flight safety. In case of an in-flight problem or other contingency, the controller/router is able to disconnect a passenger""s call in order to free channels needed for emergency communication.
Where passengers use their own telephones, billing for the calls or services may be processed in the usual manner; that is, such charges would appear on the passenger""s individual billing statement. Another feature of the infrared system is that the need for permanently-installed telephones on aircraft is reduced considerably. Because passengers are able to use their own cellular telephones (in an optical mode) the permanent telephone installations can be reduced to a few xe2x80x9cpublicxe2x80x9d stations. These stations would be available to any of the passengers, and are analogous to pay telephones in a terrestrial telephone system. Potential advantages of having fewer permanent telephone installations include reduced aircraft maintenance costs and lower installed system weight with concomitant savings in fuel.
With current on-board communications systems, flight crew moving about an aircraft""s passenger cabin are out of touch with the cockpit unless they are at a fixed intercom station. The infrared system allows members of the flight crew who are not in the cockpit to carry a small transceiver on their belts or elsewhere; their standard headset plugs into the transceiver. Alternatively, the transceiver is incorporated into the headset, or the transceiver may be configured as a xe2x80x9cwalkie-talkiexe2x80x9d device. If, during an in-flight emergency (or a non-emergency situation), a crew member needed to go into the passenger cabin to visually inspect some aspect of the aircraft such as the trailing edge of the wing, voice contact can be maintained with the cockpit all the while. The crew member can also be in real-time contact with personnel on the ground. Similarly, flight attendants may contact each other or the flight crew, as desired. Such links use the IR system aboard the aircraft and RF transmission via external antennas, as appropriate.
Another feature of the on-board network is the capability to transmit entertainment audio, such as the sound tracks of in-flight movies, to individual headsets worn by passengers. Such transmission uses optical frequencies to xe2x80x9cbroadcastxe2x80x9d one or more audio channels via the optical ports, eliminating the need for passengers to wear a plugged-in headset.
Based on the above, it is an object of this invention to provide, for use within aircraft, a communications system which uses optical frequencies rather than radio frequencies.
Another object is to increase the safety of air travel by eliminating potential sources of radio-frequency interference with an aircraft""s electronic instruments and systems.
A further object is to provide a system by which flight-recorder data and aircraft performance data may be transmitted from an aircraft to a ground station.
Another object is to provide a system for wireless communications within an aircraft, including communications between members of the flight crew.
The specific nature of the invention, as well as other objects, uses, and advantages thereof, will clearly appear from the following description and from the accompanying drawing, the different views of which are not necessarily scale drawings.